Probably more likely that 'Iceman' and 'Cyclops' are mythological figures rather than the Marvel heroes, but that definitely looks like Thor. I'm guessing it was just a little tongue-in-cheek joke that happens to be in line with the Source Wall's lore--that it's made up of the bodies of ancient gods who tried and failed to enter the Source.
Marvel and DC do little joking references to each other's characters all the time. Other examples are a reporter who looked just like Clark Kent in a Thor issue from Walt Simonson's run, and a guy dressed in red and yellow like the Flash who was referred to as a "buried alien" (i.e. Barry Allen) in some Quasar issues back in the '90s.